xtreme industries

i have owned a 4x4 in the past but i used to have to go outside, lock the hubs, then engage the 4x4 for the transfer case.
with the 2007 tahoe, i dont see any hubs, just a bearing housing and a CV axle through it. does this mean that the front axles, the differential, and the front drive shaft are turning all the time and are fully engaged but only receive power from the engine when the transfercase engages the 4x4?

please explain. much appreciated, thanks.

xtreme industries

also, if i can not afford to fix my issue, am i able to remove the front diff, axles, driveshaft and transfer case, and get a new rear shaft to make it 2wd only or is there alot more involved in converting to 2wd?

73shark

I think if you remove the front axles, the wheels will fall off. If you wanted a 2WD, why get a 4WD?

I don't think the front axles are engaged when in 2WD but could be wrong as never really looked into it.

SabrToothSqrl

in the GMT900 and most 'modern' 4x4s, the 'hubs' are always locked.

getting out to lock the hubs? what is this 1946? I've never even seen this setup. (other than hard core off roaders who want to be able to run 2WD low, or drop a hub)...

anyway, back to your question.

this Tahoe and most like it disconnect the transfer of torque from the transmission at two places.

the first is obvious, the transfer case. The second is actually 2 places. between the front diff and the hubs. the front CV joints in the tahoe will always spin, because.. well the wheels are spinning when you drive.

however by disconnecting the power transfer between the front differential and these shafts, the front drive shaft and the front diff DO NOT spin while driving around in 2WD. (better MPG, less wear and tear)

The exception to this is the Jeep Wrangler, who for simplicity, weight reduction, and durability does not have this second disconnect. on the TJ, and the JK, the front diff and drive shaft spin whenever it's moving. it's only disconnect is the transfer case. This affects MPG, but improves durability.

A high point of failure in the YJ (86-96 wrangler) was the vacuum operated rubber hosed actuation system that used to disconnect the front 'hubs' in it. This was also a point of high failure in the Tahoe actually...

the GMT900 I believe uses electronic actuators, and no longer uses an air pump and rubber hoses that tend to become brittle in cold... which causes... snow... which is about the same damn time you'd really like to use that 4 wheel drive.

Anyway, 4-auto engages either the front axle system or the transfer case when enabled (I'm not sure yet which, haven't had time to review it in detail) then when it detects that it's slipping, finishes engaging the system... (if this is incorrect, please let me know).

I've been Jeepin' since '01, and might get back into it some day, but for now I have too many other hobbies

the traction control in the GMT900 is amazing, and with my LTZs locker, it does quite well, even in 2WD, in 4WD, it's a beast.

http://en.wikipedia.org/wiki/Four-wheel_drive

73shark

Nit: 1986 was last year for CJ7 as I had one. Wished I still had it. It had manual hubs.

How do they disconnect the diff from the front drive shafts?

SabrToothSqrl

it's some sliding mechanism between the diff and the shafts.

I'm looking for a diagram, but I have the FSM at home.

actuator:
http://www.youtube.com/watch?v=S55ZEQjmKnw

I'm tired, so this is what i found:

http://ww2.justanswer.com/uploads/qu...1927_dodge.gif

that's a dodge, but the idea is similar, but you can see they used air pressure for this one, in reference to the common failure point I explained above. a sliding action engages the shafts. saves MPG, adds lots of parts and points to fail... pick your poison.